1 files changed, 23 insertions, 0 deletions
diff --git a/util.tl b/util.tl
new file mode 100644
index 0000000..71fc985
--- /dev/null
+++ b/util.tl
@@ -0,0 +1,23 @@
+(defun move-impl (items keys ins-pos)
+  (let ((key-items (mapcar (op find @1 items) keys))
+        (rm-items [set-diff items keys equal]))
+    (append [rm-items 0..ins-pos]
+            key-items
+            [rm-items ins-pos..:])))
+
+(defun minpos (items keys)
+  [reduce-left min (mapcar (op posqual @1 items) keys) (length items)])
+
+(defun move-up (items keys)
+  (move-impl items keys
+             (max 0 (pred (minpos items keys)))))
+
+(defun move-down (items keys)
+  (move-impl items keys
+             (succ (minpos items keys))))
+
+(defun move-front (items keys)
+  (move-impl items keys 0))
+
+(defun move-tail (items keys)
+  (move-impl items keys (length items)))